37515 - Mechanical and Thermal Measurements

Learning outcomes

The main objectives of the course are to introduce and discuss the main issues related to measurements on mechanical and thermal systems, to the acquisition, analysis, processing and interpretation of measurement results, and to the understanding and selection of sensors most widely used for physical quantities measurements.

Course contents

Basic principles

Measurement concept: definitions and standardisation. General measurement systems configurations. Examples of application to different application areas.

 

Static characteristics of measuring instruments

Static calibration and calibration curve. Statistical data analysis. Metrological characteristics: accuracy, sensitivity, treshold, resolution, hysteresis, linearity. Uncertainty: definitions and standardisation, analysis and determination.

 

Dynamic characteristics of measuring instruments

Introduction and general equation. I and II order instruments and response to typical inputs. Response to periodic and transient inputs. Experimental measurement od dynamic parameters.

 

Basics of signal analysis

Periodic, transient and random signals. Auto- e cross-correlation functions. Power spectral density. Frequency response to general inputs.

 

Analog-to-digital conversion

Quantisation and coding. Analog signal acquisition and conditiong. A/D converters. Sequential and simultaneous multi-channel acquisition configurations.

 

Dimension, displacement and velocity measurements

Callipers, potentiometres, LVDTs, capacitive, optical and magnetic proximity sensors. Incremental and absolute encoders.

 

Absolute displacement, velocity and acceleration measurements

Sismometers. Accelerometers and piezoelectric accelerometers. Accelerometer calibration.

 

Deformation measurements

Strain gages. Resistance strain gages: types, applications, manufacturing and fixing of sheet strain gages, Wheatstone bridge, temperature effect, strain measurement configurations.

 

Force, torque and power measurements

Scales and piezolelectric and strain gage load cells. Torquemeters. Mechanical, hydraulic and magnetic brakes.

 

Pressure measurements  

Manometers, piezoelectric, piezoresistive and capacitive pressure sensors. Dynamic calibration of pressure sensors.

 

Flow velocity measurements

Pitot tube. Hot-wire anemometer. Laser Doppler Anemometry (LDA). Particle Image velocimetry (PIV).

 

Temperature measurements  

Thermometers e thermocouples. Thermoresistances e thermistors. Infrared methods: pirometers e thermocameras.

Readings/Bibliography

E.O. Doebelin, Strumenti e Metodi di misura , McGraw Hill

R. Figliola, D. Beasley, Theory and design for Mechanical Measurements, Wiley&Sons

G. Minelli, Misure meccaniche , Patron

Teaching methods

Teaching is divided into lectures.

Assessment methods

The assessment of learning outcomes is done through an oral examination.The latter aims at verify knowledge acquired during the course, related to the main issues on the execution of measurements under both static and dynamic conditions, the operation and calibration of the most popular instruments for the measurement of physical quantities, analysed during the course and in the laboratory. The exam consists in three questions of which at least one is focused on the first part of the course, i.e. static and dynamic performance of measurement systems.

Teaching tools

Video Projector, pc

Office hours

See the website of Raffaella Di Sante